Essential Radio Astronomy

Essential Radio Astronomy (ERA) grew from lecture notes
for the one-semester radio astronomy course taken by all astronomy
graduate students at the University of Virginia. To attract advanced
undergraduates with backgrounds in astronomy, physics, engineering, or
astrochemistry to radio astronomy, we limited the prerequisites to
basic physics courses covering classical mechanics, macroscopic
thermodynamics, electromagnetism, and elementary quantum
mechanics. Prior courses covering electromagnetism with vector
calculus, electrical engineering, special relativity, statistical
thermodynamics, advanced quantum mechanics, Fourier transforms, or
astrophysics were not required. Nearly everything
in ERA has been derived from first principles in order to
fill the gaps in students’ backgrounds and make ERA a useful
reference for practicing radio astronomers.

Classical radio astronomy textbooks such as Radio
Astronomy by J. D. Kraus
emphasized radio engineering and were written for two-semester courses
that prepared students for careers in radio astronomy. In this era of
multiwavelength astronomy, most graduate students can afford to spend
only one semester studying radio astronomy, during which only the most
essential concepts can be presented. Our goal is to give them the
background needed to read and understand the radio astronomy
literature, to recognize when radio observations might help solve an
astrophysical problem, and to design, propose, and analyze radio
observations. The ERAtextbook
complements the longer and more technical Tools of Radio
Astronomytextbook
that “describes the tools radio astronomers need to pursue their
goals” in greater detail. ERA was also shaped by our belief
that radio astrophysics owes more to thermodynamics than to
electromagnetism, so Kirchhoff’s law appears more frequently than
Maxwell’s equations.

Originally, our brief lecture notes were printed and handed out to
students in the traditional classroom environment: a chalk-dusted
professor covered blackboards with equations which students faithfully
copied into their notebooks for later study. To avoid this unnecessary
work and free the students to concentrate on the ideas being
presented, we expanded the abbreviated notes into complete texts with
figures and full mathematical derivations, then converted them from
TeX to html so they could be posted to the web and projected onto a
screen in any classroom. Now the professor faces “heads up” students
who can watch, listen, and ask questions without worrying about
failing to write down a crucial step in some long derivation.

A broader goal of the National Radio Astronomy
Observatory1 is fostering the community of researchers
using radio astronomy by attracting and training the most talented
university students anywhere in the world. NRAO directors
Paul Vanden Bout, Fred Lo, and Tony Beasley have generously supported
our efforts to upgrade and expand all of the course materials
(lectures, problem sets, exams) that are now available on this
website. (The original but now obsolete web version can still be found
here.)

We hope that the combination of this book and its associated
website will facilitate teaching radio astronomy at the university
level, especially at the many colleges and universities lacking “black
belt” radio astronomers. The website can display large galleries of
color images, link to interactive demonstrations and relevant articles
on the web, present problem sets and solutions, and be updated
frequently to present new findings or report errata from the book. We
thank Princeton University Press for agreeing to a nonexclusive
copyright that allows the book and website to coexist.